1. Field of the Invention
The present invention relates to a foldable portable wireless communication apparatus, and more particularly, a foldable portable wireless communication apparatus which has a built-in antenna.
2. Description of the Related Art
Cellular phones become very popular as foldable portable wireless communication apparatuses. Some of such cellular phones incorporate an antenna in a casing, i.e., they have a built-in antenna.
For example, in a foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535, an operation-side housing provided with a transmitter microphone, a key operation section, and the like extends upward beyond a hinge section provided on one end portion of the anterior surface of the housing. The foldable cellular phone employs a structure that an antenna is housed in an area extending from below the hinge section to an extended part of the operation-side housing.
As the foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535 is structured to house the antenna behind the hinge section, the foldable cellular phone is unlikely to be affected by a human body at the time of talking, and is superior in terms of high packing density of parts.
In the case of the structure of the foldable cellular phone disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-297535, however, when a display-side housing is folded toward the operation-side housing, the antenna housing portion of the operation-side housing protrudes upwardly beyond the hinge section. Accordingly, the foldable cellular phone is not preferable in design, and has not achieved sufficient miniaturization of the casing.
In a case where a protrusive portion is not provided, as an antenna housing section is shortened in the lengthwise direction of the housing, the built-in antenna should be shortened in the lengthwise direction by what corresponds to the shortened length of the antenna housing section. Therefore, the structure having no protrusive portion is brings about a disadvantage that the gain of a vertical polarization component at the built-in antenna decreases.